State of the art tampons and methods and equipment for their manufacture are disclosed in Leutwyler, et al., U.S. Pat. Nos. 5,911,712, 5,813,102, and 5,832,576. The tampon has an insertion end, a recovery end with a recovery tape, and a central section extending between the insertion end and the recovery end. It has a compressed, generally cylindrical, solid fibrous core, from which relatively uncompressed longitudinal ribs extend radially outward. Each rib is separated from adjacent ribs in the vicinity of the compressed fiber core to an extent which is greater than that extent to which such a rib is separated from an adjacent rib remotely from the compressed fiber core. Further, the fiber core can be pressed more strongly in the central area than in the area of the recovery end of the tampon. The recovery end of the tampon can also be provided with a finger recess and the insertion end with a round dome. Finally, the tampon is at least partially surrounded by a liquid-permeable sheathing.
Such a tampon can be formed with the following steps: rolling up a length of a continuous fibrous web to form a generally cylindrical tampon blank with a circumferential surface; simultaneous radial pressing of narrow, strip-shaped sections of the circumferential surface of the tampon blank arranged in a spaced manner to form a number of longitudinal grooves which are separated from one another by relatively uncompressed longitudinal ribs which extend radially outward from a relatively compressed core, the core being compressed to a smaller extent in the area of the recovery end of the tampon than in its remaining area; and pressing of outer ends of the longitudinal ribs radially inward to form a soft, smooth circumferential surface, while the relatively uncompressed fibrous structure of the ribs is preserved. Furthermore, a finger recess and a round dome can be provided at the recovery end and the insertion end of the tampon respectively. Lastly, a liquid-permeable sheathing is fixed on the fibrous web at least in parts, so as to provide a liquid-permeable layer on at least part of the outer surface of the tampon blank.
The formation of the grooves and ribs of this state of the art tampon are known from these disclosures and that of Friese et al., U.S. Pat. No. 6,310,269, which provides a tampon, especially useful as a digital tampon, that has a densified central core and a softer outer surface.
While this tampon represents a significant improvement over the previously commercialized tampons, there remain areas susceptible to improvement. One such improvement that is desirable is increased surface area to reduce the likelihood of early leakage of fluids flowing down the surface of the tampon.
Patent literature has also suggested that coiled tampons can be formed for improved flexibility (such as disclosed in Brecht, U.S. Pat. No. 3,011,495, and Schirmer et al., U.S. Pat. No. 2,965,101) and for easier withdrawal (such as disclosed in Shimatani, U.S. Pat. No. 4,328,804, and Sneider, U.S. Pat. No. 4,351,339). These coiled tampons are generally formed by twisting one or more “ropes” of material. However, these improvements in flexibility and withdrawal characteristics appear to result in reduced column strength.
The object of the invention is to improve the tampon, the method and the apparatus as described above in such a manner that the risk of leakage after the tampon has been put into use is reduced considerably by extending the time over which the tampon absorbs body fluid, and by enlarging the surface of the tampon and increasing the fiber quantity available for immediate absorption of body fluid after the introduction of the tampon, in particularly preferred embodiments in the area of the fiber core.